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darryl
04-26-2005, 11:09 PM
Reading the recent toolpost grinder thread, I'm reminded again of the idea of using skateboard bearings for 'precision' applications. Abec 7 or 9 - shouldn't those be quite expensive, say about the cost of a small used car, considering that there's two per wheel, four wheels per skate, two skates per person (unless you're poledog, the one-legged wonder boarder). It doesn't seem right, considering that one bearing for a toolpost grinder can cost $100.
Is bull**** flying, or can you really get that precision of a bearing for a skateboard? And can anyone feel the difference? Or are the bearings for a toolpost grinder abec 15 or something?

wierdscience
04-26-2005, 11:23 PM
Oh well it's the type bearing thats the kicker.
6300 section or 6200 section or 6000 section are cheap,even in the higher grades.

But for precision grinders angular contact types are the rage.
They can be loaded to eliminate radial and axial play.

Me I would look for a Dumore or Vertex spindle on fleabay and then build the grinder around it.

Skate board wheels made really good wheels for 1" wide belt sanders.Oddly enough bronze and even babbit bearing work for toolpost grinders,so long as a method for adjusting wear is provided.

Forrest Addy
04-27-2005, 12:50 AM
A neighborhood kid once spent a weeks worth of work earned cleaning the laundromat on "super-precision" skateboard wheel bearings. I forget what size they were but they were dead common Class 1 radial bearings. He showed them to me. He paid something like $16 each. I was aghast.

I happened to have a couple of 10 pack boxes of the same make and size. I sold both to him for $16 and he went off and he sold them to his buddies at $8 each to recover his squandered funds.

I showed him how to flush the grease out of his wheel bearing so the wheel would spin forever and that REALLY impressed his buddies. He promptly started a bearing "conditioning" service charging $2 a bearing to wash a little lighter fluid through the shields.

I could have bilked the local skateboeaders for thousands supplying them with bogus stuff but I didn't have the heart for that kind of fraud.

Skateboarders are apparently as smart and focused on getting value received for their hard-earned money as hot-rodders.

J Tiers
04-27-2005, 08:31 AM
<font face="Verdana, Arial" size="2">Originally posted by wierdscience:
Oh well it's the type bearing thats the kicker.
6300 section or 6200 section or 6000 section are cheap,even in the higher grades.

But for precision grinders angular contact types are the rage.
They can be loaded to eliminate radial and axial play.

Me I would look for a Dumore or Vertex spindle on fleabay and then build the grinder around it.

</font>

For the small Dumore grinders, there are no angular contact bearings. They are relatively common radial ball bearings, which are axially preloaded by a spring in the pulley.
The $1500 packaged spindles no doubt use a better system. It had better.

It is only $25 for NOS Dumore bearings from a Dumore dealer (Sopko) for the small grinder, vs the cartridge spindle price.

I got my bearings locally, before finding out about the NOS bearings. Typical bearing house stuff.

And, no, the finish from the grinder is NOT the trash that would be predicted. It is better than I can measure.

[This message has been edited by J Tiers (edited 04-27-2005).]

wierdscience
04-27-2005, 09:54 PM
Yes that will work,loading the inner race with a spacer and spanner nut.The trick there thou is finding a bearing you like without the C3 in the suffix(C3= looser than standard tolerence)The C3's would even work,if you load them up in pairs.

Dr. Rob
04-28-2005, 12:16 AM
"Is bull**** flying, or can you really get that precision of a bearing for a skateboard? And can anyone feel the difference?"

I sincerely doubt that. IMHO the ABEC rating is only as good as the company that rated it. Example: Recently had to go buy some bearings for nephew's inline skates. Found 8-pack of bearings, ugly as hell, sorta sloppy, from Southeast Asia, in blisterpack with bad spelling, for ten bucks. Package says ABEC 7.

Somehow, I dont think so.

Second part of your Q... No, don't think so. The bearing registers and spacers were not so well made as to allow maximum performance, if I put it that way. Especially not if skating on asphalt streets.

Oh well... You pay dirt, you get manure as they say.

tattoomike68
04-28-2005, 01:53 AM
as far as high speed bearings for skate board and street luge "china bones"

they get pressed into a carbon fiber metalic fan thats also the hub, it moves air to keep it cool and that is inside urathane, they would go blasting down the road at 50 mph in idaho, they were nuts, a 6% grade and you were going to die.

http://www.hockeyoutlets.com/chbobe.html

one guy know was in the hospital for a while.(too fast)

anyway, the bearings were loose as a goose and would tighten as they got hot at high speed.

the carbon fiber metalic fan/hub cost the big bucks .

[This message has been edited by tattoomike68 (edited 04-28-2005).]

DaveS
04-28-2005, 02:49 AM
A few years back i made a toolpost grinder based on Deene Johnson's design in HSM. I went to the bearing supply and ordered two high speed bearings. I don't think they were anything special. The Ryobi laminate trimmer is rated at something like 25,000 rpm To date i have used it many times without any problems at all. there is no excessive vibration, and the finish is very good. As a test i even took a cut of ten-thou, with a feed of .003 just to see what would happen (standing well back of course). I realize that is way too deep but curiousity got the better of me. Not only was the finish acceptable but the Ryobi didn't even slow down. I was probably lucky everything didn't scatter. When Deene said that it would give performance equal to off the shelf grinders costing many times more, he wasn't kidding.!!!!!!

chief
04-28-2005, 03:26 AM
Why would you build something and then install inferior parts?
When you use cheap bearings and thing explodes you won't have save any money
because now you have to buy a glass eye
or artifical limb.
I have watch bearings come apart in gas turbines, it's big grenade.

sauer38h
04-28-2005, 08:38 PM
The "slop" has nothing to do with the ABEC class. That's due to the radial clearance, which is specified independently. ABEC gives geometrical tolerances on various dimensions of the inner and outer ways and the balls or rollers. That's all. Other components such as shields, seals, cages, lubricants, etc., and all other geometric dimensions of the bearing, such as radial play, are specified separately. Perfectly good bearings for garage door openers and pedestrian stuff like that are off the charts so far as ABEC is concerned. If you really want to spend money on your spindle don't just get ABEC 7s or 9s, get duplex pairs of them. Those are matched to each other, to automatically take out radial clearances when socked down into their housings. Then you don't have to dick around with preload springs, adjustable preload nuts, or any of that stuff. It's by far the best way to make spindles without getting really exotic - just the thing if you're looking for runout in the low tenths. Skateboarders would never notice tenths no matter what they may tell you.

wierdscience
04-28-2005, 08:47 PM
List of current US bearing mfgs-

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Short list huh?

darryl
04-29-2005, 12:38 AM
I had no problem at all reading down that list, WS. http://bbs.homeshopmachinist.net//smile.gif

Sad state of affairs. What's next to go? Condoms? Would anyone trust the import ones?

3 Phase Lightbulb
04-29-2005, 12:43 AM
<font face="Verdana, Arial" size="2">Originally posted by darryl:
Would anyone trust the import ones?</font>

Better than recycled ones.. http://bbs.homeshopmachinist.net//smile.gif

darryl
04-29-2005, 01:31 AM
Recycling is good, but ya gotta draw the line somewhere-